<!DOCTYPE HTML>
<html>

<head>

    <style type="text/css">
        .aspect-ratio {
            position: relative;
            width: 100%;
            height: 0;
            padding-bottom: 75%;
        }

        .aspect-ratio iframe {
            position: absolute;
            width: 40%;
            height: 30%;
            left: 0;
            top: 0;
        }
    </style>


</head>

<body>

    <h1> test </h1>

    <div class="aspect-ratio">
        <iframe src="https://player.bilibili.com/player.html?aid=56850347&cid=99299213&page=1" scrolling="no" border="0"
            frameborder="no" framespacing="0" allowfullscreen="true"> </iframe>
    </div>

</body>

</html>